Reddit mentions of Cables Unlimited Cat6 Crossover Adapter

The "weighty" controls are exactly what make DD tick for me (you can time your drifts to dodge red shells, as opposed to red shells immediately hitting walls in MK64). I can agree that the "tier list" of characters and karts is annoying (light karts are super OP), but it's not like that wasn't also an issue in MK64 (who can pick Yoshi first?) For me, though, the best Mario Kart experience in the land is still the 8-player mode from Double Dash. Characters and karts are assigned randomly each race, so it evens the playing field a bit, and the item balance was decent enough to make most races a photo-finish. If you can find two computers with ethernet ports, two USB-gamecube adapters, 8 controllers, and one of these, I highly recommend going through the setup to get BBA emulation working in Dolphin - it works perfectly once you get connected. I really hope MK8D can recreate that frenzied 8-player experience on the Switch (without requiring too many Switches to do it, a la MK7).

For CAINE, standard USB3.0 2.5" external HDDs would be fine. 2.5" drives so that you don't need to find additional power.
The older computer won't have USB3.0.

Anything stored on a server, unless newly updated, won't have USB3.0. Consider a laptop and doing some sort of network gigabit file transfer instead for the PST/email files. Gigabit vs USB2.0...gigabit wins hand down. Companies / enterprises have great networks and fast server storage so network is the way to go. Consider a crossover cable, might be necessary for direct server to laptop transfer, but better yet - get one of these: https://www.amazon.com/Cables-Unlimited-Cat6-Crossover-Adapter/dp/B00030BYJI
Wrap everything up in a logical image file (AD1 - FTK Imager).
Anything imaged using DD - create a compress E01 of it afterwards to save space and time later.
Get a USB3.0 Hardware write blocker for Thumb drives - then attach any USB card reader to it for other types. You can then use one of these as well for Hard Drives - https://www.amazon.com/StarTech-com-External-Docking-Station-Drives/dp/B00U8KSLA8/ref=sr_1_8?s=pc&ie=UTF8&qid=1504501191&sr=1-8&keywords=sata+hard+drive. Might be able to find something cheaper.
Tableau is a popular brand, expensive: https://www.forensiccomputers.com/tableau-t8u.html
Wibitech as well: https://www.cru-inc.com/products/wiebetech/usb-3-0-writeblocker/

With boot disks/bootable thumb drives - their equipment can do the work. Hardware write blocker now means you need a laptop to do on scene acquisition so that bumps your cost up. Make multiple disks and thumb drives - and you can do multiple things at once as opposed to a single laptop.